Piezoelectric actuators are employed across very wide-ranging areas of technology for enabling a controlling element to be operated with speed and precision. A preferred application for piezoelectric actuators in motor-vehicle engineering, for example, is in an injection valve in which the piezoelectric actuator controls the injection process, with use preferably being made therein of the piezoelectric actuator's swift dynamic response and fast controllability.
Piezoelectric actuators have at least one piezoelectric element located between two electrodes. The piezoelectric element's thickness is changed through the application of a voltage to said two electrodes, thereby enabling a controlling element to be operated. Since, however, the piezoelectric actuator's lengthening or shortening as a function of the applied voltage is relatively small, a stack comprising a multiplicity of piezoelectric elements each located between two electrodes is used as the piezoelectric actuator for injection valves. Said electrodes are advantageously connected electrically conductively to two contact pins by means of wires. The stack, wires, and contact pins are placed into, for example, a corresponding recess of a cylindrical plastic housing and said recess then filled with a potting compound. The stack is thus encased in the potting compound and protected from environmental influences. The electrodes, spaced a small distance apart, are moreover electrically insulated. Secure fixing of the stack in the plastic housing is furthermore achieved thereby. The potting compound consists of, for example, silicon.
Corresponding piezoelectric actuators are known from, for example, patent application DE 102 29 494 A1 and patent specification DE 198 44 742 C1.